In the field of dentistry, materials for treating a patient's teeth are often provided in packages that store the materials for a certain time period, for example over several months or even several years. Typically, such dental materials have to be stored in isolation from environmental influences, like moisture or air, for example, to prevent them from degrading or to prevent them from being contaminated. For that reason packages for dental materials are often hermetically sealed containers that the user may open to access the material. Such containers may be, for example, syringes or cartridges from which the dental materials can be dispensed.
A package of the type described usually includes a container for storing the dental material, and a discharge nozzle for directing the material to a desired place. A piston may be accommodated in the container, and when the piston is pushed forward it extrudes the material from the container through the nozzle. During storage, the container is typically sealed at one end by the piston, and at the other end by a cap. Alternatively, the container may comprise two or more dental materials, such as two or more components of a multi-component material separated in different chambers, and pistons accommodated in the respective chambers. The container may be used, for example, with a dispensing gun or device having a plunger or plungers for advancing the piston(s) within the container to dispense the material(s) in a desired location.
During manufacturing the containers are usually filled with the dental material and subsequently sealed by assembly of an appropriate closure, for example sealed with a cap and a piston. In recent years efforts have been undertaken to improve the assembly of parts, for example by improving the designs of the parts, because assembly often contributes a considerable portion of the container manufacturing costs.
Another area which has been the focus of developments in recent years is related to the filling packages with reduced inclusion of air with the dental material. This is because air included with the material stored in a package may cause the material to change, for example to harden or degrade. Furthermore, air, due to its compressibility, may cause dispensing inaccuracies and after-flow, for example, both of which cause difficulties for dental professionals. For example, WO 2006/132932 A1 discloses a system for storing and dispensing a material and a method for substantially air-free filling of a container with the material. The system comprises a container for storing an amount of a material, a piston and a front plug. The container comprises a vent that cooperates with the piston to allow air that is trapped in the container to escape. The piston together with the front plug are used to seal the material in the container.
Often the user needs to assess the optical characteristics of the material contained in the package prior to using the material, so that the optical characteristics of the material can be substantially matched to the appearance of the tooth to be restored. The optical characteristics include not only the color of the material, but also the translucency, for example. There are packages that include a part, such as a label, which is colored according to a color coding system to indicate the approximate optical characteristics of the material contained. Such system, for example, is based on individual colors that represent different optical shades of a dental material. The color system typically uses clearly distinguishable individual colors that provide for easy determination between different packages.
In EP 0 783 281 B1 a syringe system is disclosed for matching tooth composite colors to natural tooth color. The system includes a plurality of syringes. A part of each of the syringes carries a visible sample of the material contained in the syringe that is supposed to be compared to the color of a tooth.
Although some recently-developed packages offer advantages, there is still a need for a package that can be easily manufactured. In particular there is a desire to reduce the amount of parts required to make the package. There is also a desire to provide a method of making packages with a minimum number of assembly steps. Furthermore, there is still the need for minimizing the amount of air included in a package of dental material. In particular, there is a desire for that effect in combination with a package made of a minimum number of parts and/or assembly steps.